In electrophotography, also known as xerography, electrophotographic imaging or electrostatographic imaging, the surface of an electrophotographic plate, drum, belt or the like (imaging member or photoreceptor) containing a photoconductive insulating layer on a conductive layer is first uniformly electrostatically charged. The imaging member is then exposed to a pattern of activating electromagnetic radiation, such as light. Charge generated by the photoactive pigment move under the force of the applied field. The movement of the charge through the photoreceptor selectively dissipates the charge on the illuminated areas of the photoconductive insulating layer while leaving behind an electrostatic latent image. This electrostatic latent image may then be developed to form a visible image by depositing oppositely charged particles on the surface of the photoconductive insulating layer. The resulting visible image may then be transferred from the imaging member directly or indirectly (such as by a transfer or other member) to a print substrate, such as transparency or paper. The imaging process may be repeated many times with reusable imaging members.
The manufacture of lightweight coated papers for use in digital imaging systems has been largely unsuccessful for paper manufacturers. “Lightweight” is generally known to be less than 120 gsm, and typically, 90 gsm. Without specific knowledge of the driving forces behind runnability, or how well a paper runs on printing press, a manufacturer would need to run many expensive production trials in order to hopefully find a way to manufacture lightweight coated paper that exhibits good runability.
To achieve a successful product by iteration is costly, time-consuming and has a relatively low level of success. Even if this iterative process is successful, the manufacturer then runs the risk of not being certain of which parameters are driving the desired performance, and it would be difficult to consistently repeat the desired performance. It is very costly to run a design of experiment (DOE) on the paper machine to determine which factors are driving the acceptable performance. The alternative choice would be to leave all manufacturing parameters static to avoid impacting performance, but this option would result in less flexible and more costly manufacturing as some manufacturing variables that are not critical to performance would be left static. Additionally, assessing performance without a predictive measure of runability would require access to expensive equipment. Predictive testing for lot acceptance would also require large runs of paper on digital equipment (such as Xerox Corporation DC2060 or iGen3 digital imaging systems), exhausting time and money and generating a large quantity of waste. For example, over 10,000 sheets of paper may be required to fully assess “jam rate.” Jam rate is also referred to as the shut down rate (SDR). This rate is the number of times per 10,000 sheets run that the equipment shuts down or jams. In order to determine whether a product will have a low SDR, large quantities of paper need to be run to be statistically significant. Having a predictive test that could be performed on 1 or 2 sheets of paper to predict the same would save significant time and money.
Thus, there is a need to find a method for determining a relationship function linking performance to a measurable parameter or property. More specifically, there is a need for a predictive method that could be used to evaluate print substrates, especially lightweight coated paper substrates, so that digitally optimized print substrates can be successfully and consistently manufactured without large amounts of time or money.